Clinical and functional characteristics of intraoperative motor evoked potentials monitoring in microdiscectomy

Aim. To assess motor evoked potentials parameters in a complex of intraoperative neurophysiological monitoring at the time of discectomy for a herniated intervertebral disc under general anesthesia, to determine their dependence on age, sex, height.

Methods. Intraoperative motor evoked potentials monitoring during microdiscectomy under inhalational anesthesia was conducted in 43 patients for the herniated disc at L4-L5 or L5-S1 levels. In all patients, the herniated disc diagnosis was confirmed by the magnetic resonance imaging data. Monitoring was performed using the «Neuro-IOM» device («Neurosoft», Russia). Latency and amplitude of muscle response for m. abductor hallucis and m. tibialis anterior were analyzed.

Results.. The obtained data suggest that the motor evoked potentials allow to objectify the presence of motor disorders, which persist at the end of microdiscectomy. The data on the relationship between latency of muscles responses on the side of radiculopathy and the healthy side with patients’ age, body height and weight are obtained. The motor evoked potentials amplitude had a direct correlation with the patients’ body weight. Increase in latency of transcranial motor evoked potentials on the side of the clinical motor fall-out compared with the healthy limb was defined. Due to the expressed variability of motor evoked potentials responses amplitude under general anesthesia, significant differences for a given parameter were not obtained.

Conclusion. There is relationship between latency of motor evoked potentials and patients’ age, body height and weight; an increase in the latency of transcranial motor evoked potentials on the side of the clinical motor fall-out compared with the healthy limb was revealed.